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BARSIC [14]
2 years ago
14

How many ways can we pick three distinct integers from {1, 2, ..., 15} such that their sum is divisible by 3?

Mathematics
1 answer:
gogolik [260]2 years ago
5 0

Answer:

Clearly from 1 to 15 we can only have the sum 6,9,12 and 15 to be divisible by 3.

Now meaning we have 4! ( 4 factorial) which implies 4x3x2x1= 24 .

We have 24 ways to pick distinct integers that are divisible by 3.

Step-by-step explanation:

The first thing you need to do is to look for numbers that are divisible by 3. Then you take its factorial

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A rectangle is 4 cm longer than it is wide, and its area is 117 cm2 . find its dimensions.
Brilliant_brown [7]
The area of a rectangle is equal  L x  W   

4 cm longer than it is wide   L = 4 + <span>W
</span>
L x  W = 117     we replace L here 

(4 + <span>W ) x W = 117 
</span>
4W + W ^2  = 117 

<span>4W + W ^2  -117 = 0
</span>W ^2 +4 W -117 = 0

W² + 4W - 117 = 0

<span>
THEN u want to use the </span>use the quadratic formula
 

OR Factoring gives us

(W + 13)(W - 9) = 0

W = -13 or 9

But it can't be negative, so

W = 9  and L= 9+4 = 13
3 0
2 years ago
Read 2 more answers
The graph shows the amount of dirt left to remove, y, with respect to number of loads of dirt, x. Use the graph to complete each
Tema [17]

Part 1. When x=0, then y=900 (from the graph). This means that y-intercept is at point (0,900).

Answer Part 1: 900

Part 2. The y-intercept is at point (0,900). This means that at x=0 (loads), the total amount of dirt to remove is 900 cubic feet.

Answer Part 2: the total amount of dirt to remove.

7 0
1 year ago
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The track team is trying to reduce their time for a relay race. First they reduce their time by 2.1 minutes. Then they are able
konstantin123 [22]

Answer: 15.7 minutes

Step-by-step explanation:

Let x be the time in the beginning (in minutes).

Given: The track team is trying to reduce their time for a relay race.

First they reduce their time by t_1=2.1 minutes.

Then they are able to reduce that time by t_2=10

If their final time is 3.96 minutes, then

x-t_1-t_2=3.6\\\Rightarrow\ x=3.6+t_1+t_2\\\Rightarrow\ x=3.6+2.1+10\\\Rightarrow\ x= 15.7

Hence, their beginning time was 15.7 minutes.

7 0
2 years ago
Jan accidentally ran 7 minutes longer than she was supposed to. Write an expression for the total amount of time Jan ran if she
vovangra [49]

Answer:

m+7

Step-by-step explanation:

If she ran 7 minutes longer and m represents the amount of time she ran, then it would just be addition.

Let's say m=60 minutes. She would've ran for 67 minutes, which is also m+7.

6 0
2 years ago
You found $6.60 on the ground at school, all in nickels, dimes, and quarters. you have twice as many quarters as dimes and 42 co
Veseljchak [2.6K]
Let the number of nickels found be n, the number of dimes be d and the number of quarters be q.

i) "you have twice as many quarters as dimes and 42 coins in all."

means that 2d=q, and n+d+q=42

we can reduce the number of unknowns by substituting q with 2d:

n+d+q=42
n+d+2d=42
n+3d=42

We can write all n, d and q in terms of d as follows:

there are n=42-3d nickels, d dimes and q=2d quarters.

ii) In total there are $6.60 dollars,

1 nickel     =  5 cent   =  $0.05
1 dime      =  10 cent  =  $0.1
1 quarter   =  25 cent  = $0.25 

thus

(42-3d)*0.05 + d*0.1 +2d*0.25= $6.60

2.1 - 0.15d+0.1d+0.5d=6.60

2.1+0.45d=6.6

0.45d=6.6-2.1=4.5

d=4.5/0.45=10

iii)

so, there are 10 dimes, 2d=2*10=20 quarters and 42-3d=42-3*10=12 nickels.


Answer: 10 dimes, 20 quarters, 12 nickels
8 0
1 year ago
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